Attaching Zanamivir to a Polymer Markedly Enhances Its Activity Against Drug-resistant Strains of Influenza a Virus

Effects of the commercial drug zanamivir (Relenza?) covalently attached to poly-l-glutamine on the infectivity of influenza A viruses are examined using the plaque reduction assay and binding affinity to viral neuraminidase (NA). These multivalent drug conjugates exhibit (i) up to a 20,000-fold improvement in anti-influenza potency compared with the zanamivir parent against human and avian viral strains, including both wild-type and drug-resistant mutants, and (ii) superior neuraminidase (NA) inhibition constants, especially for the mutants. These findings provide a basis for exploring polymer-attached inhibitors as more efficacious therapeutics, particularly against drug-resistant influenza strains.     

Feasibility of a lifestyle intervention in early pregnancy to prevent deterioration of glucose tolerance

Background  

In conjunction with the growing prevalence of obesity and the older age of pregnant women gestational diabetes (GDM) is a major health problem.     

Mechanism of inactivation of influenza viruses by immobilized hydrophobic polycations

N,N-dodecyl,methyl-polyethylenimine coatings applied to solid surfaces have been shown by us to disinfect aqueous solutions of influenza viruses. Herein we elucidate the mechanism of this phenomenon. Infectivity-, protein-, RNA-, and scanning electron microscopy-based experiments reveal that, upon contact with the hydrophobic polycationic coating, influenza viruses (including pathogenic human and avian, both wild-type and drug-resistant, strains) irreversibly adhere to it, followed by structural damage and inactivation; subsequently, viral RNA is released into solution, while proteins remain adsorbed.     

Overweight and obesity among patients attending a Nigerian oral surgery clinic: implications for oral surgical practice in Nigeria

Aim

To determine the prevalence of overweight and obesity among patients attending oral and maxillofacial outpatient clinic of the Lagos University Teaching Hospital, Nigeria; and discuss the clinical and surgical implications that obesity has on the delivery of oral and maxillofacial surgical and anaesthetic care.

Methods

Consecutive patients presenting to the oral and maxillofacial surgery outpatient clinic at the Lagos University Teaching Hospital, Nigeria over a 4-month period (May–August 2004) were screened for age, sex, height and weight. All of the patients were treated for dentoalveolar surgical procedures (routine and surgical extractions), incisional and excisional biopsies, and enucleation under local anaesthesia.

Results

The BMIs of the studied patients ranged from 16.7 to 39.8 kg/m², with a mean of 24.6 ± 4.5 kg/m². Prevalence of excess weight was 39.1%. Thirty-one (11.4%) patients were obese and 75 (27.7%) patients were overweight. A significant difference was observed in the BMIs of male and female patients (P=0.000). The age groups < 30 years had mean BMIs that were considered normal; whereas other age groups above 30 years had mean BMIs that were considered overweight. Prevalence of obesity increases with increasing age. Obese individuals were seen in all the age groups except those < 20 years.

Conculsions

The prevalence of excess weight (overweight and obesity) in patients presenting in the studied oral and maxillofacial outpatient setting was 39.1%. Oral and maxillofacial surgeon needs to be aware of obesity-/overweight-related medical and surgical issues and take them into consideration when treating these patients.     

Novel TMPRSS6 mutations associated with iron‐refractory iron deficiency anemia (IRIDA)

Mutations leading to abrogation of matriptase‐2 proteolytic activity in humans are associated with an iron‐refractory iron deficiency anemia (IRIDA) due to elevated hepcidin levels. In this paper we describe 12 IRIDA patients belonging to 7 unrelated families and identify 10 (9 novel) TMPRSS6 mutations spread along the gene sequence: 5 missense, 1 non sense and 4 frameshift. The frameshift and non sense mutations are predict to result in truncated protein lacking the catalytic domain. The causal role of missense mutations (Y141C, I212T, R271Q, S304L and C510S) is demonstrated by in silico analysis, their absence in 100 control chromosomes and the high conservation of the involved residues. The C510S mutation in the LDLRA domain in silico model causes an intra‐molecular structural imbalance that impairs matriptase‐2 activation. We also assessed the in vitro effect on hepcidin promoter and the proteolytic activity of I212T and R271Q variants demonstrating a reduced inhibitory effect for the former mutation, but surprisingly a normal function for R271Q which appears a silent mutation in vitro. Based on mRNA expression studies I212T could also decrease the total amount of protein produced, likely interfering with mRNA stability. Collectively, our results extend the pattern of TMPRSS6 mutations associated with IRIDA and propose a model of causality for some of the novel missense mutation. © 2010 Wiley‐Liss, Inc.     

Oncologic complications of human immunodeficiency virus infection: changing epidemiology, treatments, and special considerations in the era of highly active antiretroviral therapy

Although highly active antiretroviral therapy (HAART) has revolutionized the treatment of human immunodeficiency virus (HIV)-positive patients, malignancies in the setting of HIV infection remain an appreciable problem. We evaluated the changing epidemiology of HIV-related malignancies, optimal neoplastics and their effect on viral dynamics, and evidence regarding drug interactions between chemotherapy and antiretrovirals. A MEDLINE search (January 1966-June 2006) was performed to identify clinical trials, review articles, and meta-analyses; abstracts from HIV conferences were also searched. Survival of patients with HIV-related malignancies has substantially improved since the advent of HAART. Chemotherapy for malignancies in the HIV-positive population generally resembles that for the HIV-negative population, with trials revealing an elevated frequency of toxicities in HIV-positive patients. Studies of antineoplastics have shown no long-term adverse effects on viral dynamics in terms of immunologic or virologic HIV markers. Limited pharmacokinetic data with antineoplastics and antiretrovirals suggest possible changes in some pharmacokinetic parameters, but these results should be interpreted cautiously because of the small numbers of patients enrolled in the trials. Researchers also report an increased frequency of chemotherapy-related toxicities when HAART was coadministered with antineoplastics. This increase was likely due to impairment of cytochrome P450 metabolism of antineoplastics by protease inhibitors. Because of the survival benefits of HAART, the integration of antiretrovirals with chemotherapy is now preferred for patients with HIV-related malignancies. However, because the metabolic pathways of many of these agents are similar, the effectiveness of antineoplastic therapy and its related toxicities should be vigilantly monitored in this patient population.     

Identification of Novel Superior Polycationic Vectors for Gene Delivery by High-throughput Synthesis and Screening of a Combinatorial Library

Purpose Low efficiency and toxicity are two major drawbacks of current non-viral gene delivery vectors. Since DNA delivery to mammalian cells is a multi-step process, generating and searching combinatorial libraries of vectors employing high-throughput synthesis and screening methods is an attractive strategy for the development of new improved vectors because it increases the chance of identifying the most overall optimized vectors. Materials and Methods Based on the rationale that increasing the effective molecular weight of small PEIs, which are poor vectors compared to the higher molecular weight homologues but less toxic, raises their transfection efficiency due to better DNA binding, we synthesized a library of 144 biodegradable derivatives from two small PEIs and 24 bi- and oligo-acrylate esters. A 423-Da linear PEI and its 1:1 (w/w) mixture with a 1.8-kDa branched PEI were cross-linked with the acrylates at three molar ratios in DMSO. The resulting polymers were screened for their efficiency in delivering a β-galactosidase expressing plasmid to COS-7 monkey kidney cells. Selected most potent polymers from the initial screen were tested for toxicity in A549 human lung cancer cells, and in vivo in a systemic gene delivery model in mice employing a firefly luciferase expressing plasmid. Results Several polycations that exhibited high potency and low toxicity in vitro were identified from the library. The most potent derivative of the linear 423-Da PEI was that cross-linked with tricycle-[5.2.1.0]-decane-dimethanol diacrylate (diacrylate 14), which exhibited an over 3,600-fold enhancement in efficiency over the parent. The most potent mixed PEI was that cross-linked with ethylene glycol diacrylate (diacrylate 4) which was over 850-fold more efficient than the physically mixed parent PEIs. The relative efficiencies of these polymers were even up to over twice as high as that of the linear 22-kDa PEI, considered the “gold standard” for in vitro and systemic gene delivery. The potent cross-linked polycations identified were also less toxic than the 22-kDa PEI. The optimal vector in vivo was the mixed PEI cross-linked with propylene glycol glycerolate diacrylate (diacrylate 7); it mediated the highest gene expression in the lungs, followed by the spleen, with the expression in the former being 53-fold higher compared to the latter. In contrast, the parent PEIs mediated no gene expression at all under similar conditions, and injection of the polyplexes of the 22-kDa PEI at its optimal N/P of 10 prepared under identical conditions killed half of the mice injected. Conclusions High-throughput synthesis and transfection assay of a cross-linked library of biodegradable PEIs was proven effective in identifying highly transfecting vectors. The identified vectors exhibited dramatically superior efficiency compared to their parents both in vitro and in an in vivo systemic gene delivery model. The majority of these vectors mediated preferential gene delivery to the lung, and their in vivo toxicity paralleled that in vitro.     

Association between administered oxygen, arterial partial oxygen pressure and mortality in mechanically ventilated intensive care unit patients

Introduction

The aim of this study was to investigate whether in-hospital mortality was associated with the administered fraction of oxygen in inspired air (FiO₂) and achieved arterial partial pressure of oxygen (PaO₂).

Methods

This was a retrospective, observational study on data from the first 24 h after admission from 36,307 consecutive patients admitted to 50 Dutch intensive care units (ICUs) and treated with mechanical ventilation. Oxygenation data from all admission days were analysed in a subset of 3,322 patients in 5 ICUs.

Results

Mean PaO₂ and FiO₂ in the first 24 h after ICU admission were 13.2 kPa (standard deviation (SD) 6.5) and 50% (SD 20%) respectively. Mean PaO₂ and FiO₂ from all admission days were 12.4 kPa (SD 5.5) and 53% (SD 18). Focusing on oxygenation in the first 24 h of admission, in-hospital mortality was shown to be linearly related to FiO₂ value and had a U-shaped relationship with PaO₂ (both lower and higher PaO₂ values were associated with a higher mortality), independent of each other and of Simplified Acute Physiology Score (SAPS) II, age, admission type, reduced Glasgow Coma Scale (GCS) score, and individual ICU. Focusing on the entire ICU stay, in-hospital mortality was independently associated with mean FiO₂ during ICU stay and with the lower two quintiles of mean PaO₂ value during ICU stay.

Conclusions

Actually achieved PaO₂ values in ICU patients in The Netherlands are higher than generally recommended in the literature. High FiO₂, and both low PaO₂ and high PaO₂ in the first 24 h after admission are independently associated with in-hospital mortality in ICU patients. Future research should study whether this association is causal or merely a reflection of differences in severity of illness insufficiently corrected for in the multivariate analysis.     

Precision estimates of relative and absolute cerebral blood flow in Alzheimer’s disease and cognitively normal individuals

Alzheimer’s disease is characterized by regional reductions in cerebral blood flow (CBF). Although the gold standard for measuring CBF is [¹⁵O]H₂O PET, proxies of relative CBF, derived from the early distribution phase of amyloid and tau tracers, have gained attention. The present study assessed precision of [¹⁵O]H₂O derived relative and absolute CBF, and compared precision of these measures with that of (relative) CBF proxies. Dynamic [¹⁵O]H₂O, [¹⁸F]florbetapir and [¹⁸F]flortaucipir PET test-retest (TrT) datasets with eleven, nine and fourteen subjects, respectively, were included. Analyses were performed using an arterial input model and/or a simplified reference tissue model, depending on the data available. Relative CBF values (i.e. K₁/K₁′ and/or R₁) were obtained using cerebellar cortex as reference tissue and TrT repeatability (i.e. precision) was calculated and compared between tracers, parameters and clinical groups. Relative CBF had significantly better TrT repeatability than absolute CBF derived from [¹⁵O]H₂O (r = −0.53), while best TrT repeatability was observed for [¹⁸F]florbetapir and [¹⁸F]flortaucipir R₁ (r = −0.23, r = −0.33). Furthermore, only R₁ showed, better TrT repeatability for cognitively normal individuals. High precision of CBF proxies could be due to a compensatory effect of the extraction fraction, although changes in extraction fraction could also bias these proxies, but not the gold standard.